There should really just be a "Chrome" config template for Firefox for people that prefer Chrome UX and styling.
But in general, it's very upsetting that Firefox doesn't actively support editing these user setting fields.
My experience was that if you changed even a single boolean value, the answer to every support question was "reset to default settings and see if it's still broken". Just awful.
Setting the "browser.tabs.tabMinWidth" preference to 0 in Firefox will let the tabs shrink down fairly small (to just the favicon and maybe one letter of the title). If you want the tabs to shrink even more than that, I'd like to understand why, other than "it's what I'm used to". Which, to be clear, is a perfectly valid reason to want something!